Ahhh, but the moon IS hollow, so is the earth and the sun and likely other planets too.

Quoting: Anonymous Coward 8640456

Apollo 13 was headed homeward. Moments later the 15-ton spent third stage of the Saturn V launch vehicle crashed into the Moon, as planned.

It occurred at 8:09 p.m. EST, April 14. The S-IVB struck the Moon with a force equivalent to 11 1/2 tons of TNT. It hit 85 miles west northwest of the site where the Apollo 12 astronauts had set up their seismometer. Scientists on Earth said, "the Moon rang like a bell."